In 2010, in light of the recent discovery that STXBP2 mutations are responsible for a proportion of FHLH cases, we re-examined samples from the cohort of patients we had planned to include in our new genetic linkage study of FHLH. As we found STXBP2 mutations in some of these patients, those patients were dropped from the planned study. Therefore, we are accruing additional new patients and have validated their lack of known mutations and normal expression of candidate genes. In parallel, we have also prepared keratinocyte cultures from skin biopsies to improve the efficiency of generating induced pluripotent stem cells from normal healthy volunteers and patients.